Der war mir jetzt neu:
Mächtiger SET Befehl.
Remove both Ends – Remove the first and the last character of a string
WiX tricks and tips – Stack Overflow
Use heat to harvest files with wildcard Guid. Useful if you want to reuse WXS files across multiple projects see my answer on multiple versions of the same product. For example, this batch file automatically harvests RoboHelp output.